Magnet wire for hermetic motors

Abstract

A magnet wire suitable for use in hermetic motors comprising a conductor wire, an insulating intermediate layer, a polyamide outer layer, and an organic polymeric lubricant coating on the outer layer. The lubricant has a pour point below about 15° F. (-9° C.) and wets the outer layer. A preferred lubricant is soluble in monochlorodifluoromethane and in dichlorodifluoromethane, and comprises a saturated C 2 -C 4 ether of ethylene oxide and 1,2-propylene oxide copolymers. A particularly preferred lubricant has a viscosity of about 100 to 400 SUS (21 to 87 centistokes) and a pour point of about -60° F. (-51° C.).

What is claimed is: 
     
       1. A magnet wire suitable for use in an hermetic motor environment comprising a conductor wire;   an insulating intermediate layer adjacent and exterior to said conductor wire;   a polyamide outer layer adjacent and exterior to said intermediate layer, said polyamide being selected from the group consisting of polyundecaneamide, polydodecaneamide, and mixtures and copolymers thereof; and   an organic polymeric lubricant adjacent and exterior to said outer layer, said lubricant comprising a saturated C 2  -C 4  ether of ethylene oxide and 1,2-propylene oxide copolymers, the ratio of ethylene oxide to propylene oxide being about 1:1 to 3:1; said lubricant having a pour point below about 15° F., a viscosity at 100° F. of about 100 to 400 SUS, and a molecular weight of about 200 to 800; said lubricant wetting the outer layer, and being soluble in monochlorodifluoromethane and dichlorodifluoromethane.   
     
     
       2. The magnet wire of claim 1 wherein the pour point of said lubricant is about -60° F. 
     
     
       3. The magnet wire of claim 1 wherein said lubricant comprises a monobutyl ether of ethylene oxide and 1,2-propylene oxide copolymers. 
     
     
       4. The magnet wire of claim 1 wherein said magnet wire is self-bondable at elevated temperatures in the range of about 160° to 200° C., and said polyamide is polyundecaneamide. 
     
     
       5. The magnet wire of claim 1 wherein said intermediate layer comprises a completely organic, thermosetting, modified polyester. 
     
     
       6. The magnet wire of claim 1 wherein said intermediate layer comprises a blend of (a) a polymeric amide-imide-ester comprising the reaction product of (i) trimellitic anhydride,   (ii) an aromatic primary diamino compound, and   (iii) a polyol component, at least a portion of which is tris(2-hydroxyethyl) isocyanurate; and     (b) a polyester comprising the reaction product of (i) an aromatic carboxylic acid, and   (ii) a polyol component, at least a portion of which is tris(2-hydroxyethyl) isocyanurate.     
     
     
       7. The magnet wire of claim 1 wherein said intermediate layer comprises about 50 to 80% of the total coating thickness, and said outer layer comprises about 20 to 50% of the total coating thickness.